Expansible mandrel



June 28, 1955 K. E. L. GRETTVE EXPANSIBLE MNDREL 4 Sheets-Sheet l FiledDec. 27 1951 ./A/vE/Vrwe K, E L. Gxerrr ,4a/wem' June 28, 955 K E L,GRETTVE 2,7l 1,863

EXPANSIBLE MANDREI..

Filed Dec. 27, 1951 l I 4 Sheets-Sheet 2 fig ,l N 115W@ wen/Tof. K, E. LGRev--n/E Jun@ 28, 1955 K. E. L. GRETTVE n HLSW EXPANSIBLE MNDREL FiledDeo. 27. 1951 4 sheets-sheet s June 28, `1955 K. E. L.' GRETTVEEXPANSIBLE MANDREL 4 Sheets-Sheet 4 Filed bec. 27, 1951 nited StatesPatent EXPANSIBLE MANDREL Karl Einar Lage Grettve, Lilla Edet, Sweden,assignor to Lilla Edets Pappersbruks AB, Lilla Edet, Sweden, acorporation of Sweden Application December 27, i951, Serial No. 263,653Claims priority, application SwedenNovember 12, 1951 14 Claims. (Cl.242-1-72) The present invention relates to winder mandrels, and, inparticular, to mandrels carrying cardboard tubes or cores on which websof sheet material such as paper may be wound. More specifically, thisinvention relates to expansible Winder mandrels for rolls of paper, saidmandrel comprising a shell, on which the cardboard tube is passedendwise, and a pneumatic expansible means inserted within the shell, thedevice being such that when forcing air into the expansible means theshell will be pressed radially outwards against the cardboard tube,which on account of the friction between the latter and the shell iscaused to rotate with the mandrel. Formerly, the expanding means wasconstituted by one or more double-walled bags of rubber or some otherelastic material. These bags are comparatively expensive tomake, and,besides, they are difficult to attach to the mandrel.

One of the objects of the present invention is to simplit'y theproduction of such mandrels besides which several other advantages areobtained. Characteristic of the invention is the fact that the expandingmeans comprises a hose which is passed over a shaft which passes throughthe mandrel and is attached to the shaft in such a way that the ends ofit hold tightly to the shaft which is provided with a device forintroducing compressed air into the space between the hose and theshaft, besides which an expanding shell is applied round the outside ofthe hose, which shell is provided with longitudinal bars which aremutually joined at the ends and are here carried by the shaft.

in the following the invention will be explained with reference to theattached drawings, in which Fig. l is a side view of a mandrel accordingto an embodiment of the invention and Fig. 2 is a similar side view ofthe mandrel as per a somewhat altered embodiment of the invention. Fig.3 shows a longitudinal section of one end of the mandrel drawn to alarger scale. Fig. 4 is :a

side View of the opposite end of a mandrel as per a somewhat alteredembodiment of the invention. Fig. 5 is a cross section through themandrel along the line V-V in Fig. 4, and Fig. 6 is a similar crosssection but along the line VI-Vl in Fig. 4. Fig. 7 is an end view of aring for clamping the one end of the hose around the shaft passingthrough and Fig. 8 is a vertical section through the ring along the lineVIH-VIII in Fig. 7. Fig. 9 is a side view, partly in longitudinalsection, of a mandrel as per still another embodiment of the invention.Fig. 1G is a cross section through the mandrel along the line iX--EX inFig. 9. Fig. 1l is a side view of the middle part of a relatively longmandrel of the construction shown in Fig. 9. Fig. l2 is a longitudinalsection through the one end of the mandrel showing another constructionof the device for clamping the hose to the shaft passing through it.Fig. 13 is a longitudinal section through the one end of a mandrelarranged to be pumped up by a handpump.

In the embodiment shown in Figs. l3 the main parts of the mandrel are ashaft 1, a hose 2 of rubber or some other suitable elastic materialpassed over the shaft and rice a steel tube, or shell 3, which at eitherend is supported by a housing 4 which is attached to the shaft by meansof a crosswise inserted pin 5. The shell is attached to each housing 4by a screw 6. Around either end of the hose 2 a helical spring ring 7 ispassed which by cooperation between a ring-shaped part S, which servesas an abutment, and a clamp ring 10 provided with a conical clampsurface 9, is pressed against the outside of the hose. The clamping iseffected by moving the ring-shaped part 8 and the clamp ring 10 againsteach other, causing the ring 7 to press the hose 2 around the shaft 1 sothat a good tightening is obtained. The ring-shaped part 8 and the clampring 10 are kept in the position they have been moved into byindentations or tongues 11 pressed inwards in the outer rim of the clampring. The shaft 1 is provided with an axial bore 12 and with a radialchannel 13, by which the bore 12 communicates with the space 14 betweenthe shaft and the inside of the hose 2. At the outerend the boring 12 isprovided with screw threads 15, fitting to a nipple 16 with an axiallyarranged valve 17 of the type which is used on prevailing pneumatictires on motor cars. The valve is thus provided with a valve plug 18which is arranged to be pressed inwards by the air current from acompressed air conduit, and after that by means of the air pressureestablished in the bore 12 is pressed to a tightening Contact against aseat in the valve body. Between a cup-shaped part 19 of the nipple 16for protecting the valve i7 and the outer end of the shaft l, a packingring 20 is inserted. ln the steel tube 3 a number of longitudinal slits21 are made, which according to Fig. 1 extend along the whole tube andcease in the neighbourhood of the ends of the tube. The bar-shaped partsbetween the slits Z1 are indicated by 22.

When compressed air is let in through the valve 17 and further throughthe bore 12, the channel 13 and into the space 14 between the shaft 1and the hose 2, the latter is expanded and thereby presses the bars 22bow like outwards against a cardboard tube 23 passed over the expansibleshell 3, on which the paper is to be Wound. The friction between theexpansible shell 3 and the tube 23 will then be suicient to cause thetube to rotate with the mandrel.

If the expansible shell 3 is relatively long it may be appropriate tomake the slits in the tube to leave at the middle of the tube a part 24unslitted. In such case the bars 22 on either side of said part 24 willbend outwards arc-like under the internal air pressure, whilst theunslitted part 24 will remain unaffected.

Instead of slitting up a metal tube the expansible shell 3 can beestablished by joining a number of steel bars 22 so that an expansibleshell of polygonic cross section is formed (see Figs. 5 and 6). Thesteel bars 22 are mutually welded together at the ends as indicated at2S in Figs. 4 and 6. The advantage of this construction is that the bars22', when they are bent outwardly, by their side edges 26 will gripfirmly in the tube 23 whereby a good friction is established. When theair is let out from the space 14 between the hose 2 and the shaft 1,which is accomplished by pushing the valve plug 18 inwards, the bars 22will spring back again into their straight initial position and thecardboard tube 23 can easily be pulled of the mandrel without the innerwinding of thc cardboard tube being attached to the tube, which oftenhappens when cylindrical expansible shells are used.

In Figs. 9 to l1 incl. an imbodiment of the driving mandrel is shown inwhich the expansible shell has been given still another form. Here thesteel bars 22 are not welded together. Their ends 27 are shaped so thattheir side edges 28 converge radially outwardly. These ends are put indovetail slots 29 in the housings 4. By this arrangement the bars 22during their arc-like bend ing outwards under the internal air pressurewill be able to slide axially a little with their ends in the dovetailslots 29. In the disclosure according to Figs. 9 to ll incl. the shaft 1consists of a tube with an axial bore 12. In this case a nipple 16provided with a valve 17 may be attached at either end of the shaft l.However, one of the ends can also be closed by means of a screw plug 3Gwith a tightening ring 20 inserted between the corresponding end of theshaft and a iiange 31 on the screw plug.

lf the mandrel is relatively long, a housing 4' can be attached to theshaft i placed approximately at the middle of the shaft and fixed to thelatter by means of a pin 5. This housing 4 corresponds in its shape withthe housings -l at the ends of the shaft, with the exception that thehousing 4 is provided with grooves 29 which extend along the wholelength or the housing. 'i he bars 22"' at either side of the housing 4consequently can be bent arc-like outwardly by action of the internalair pressure.

In Fig. 3 a helically wound ring 7 is used for clamping the end of thehose 2 to the shaft l. However, also a ring 32, preferably of steel andof the shape shown in Figs. 7 and S can be used. This ring at its endsis provided with a step 33 and the ends of the ring overlap each otheras shown especially in Fig. 8.

In Fig. 12 a device is shown by which the tightening of the hose 2around the shaft is simplified. According to this embodiment on bothends of the shaft is passed a piece of hose 34 of comparatively thinrubber material and the hose 2 is at its corresponding end fixed to thepiece of hose 34 by way of example, by rubber solution in such a waythat the inner end 35 of the piece of hose 34 protrudes freely into thehose 2. The end of the hose 2 is kept firmly pressed against the shaft 1by a metal strip 36 or the like. The internal pressure in the space iftwill press the inner end 35 of the piece of hose 34 into a tighteningcontact with the outer side of the shaft 1.

In the embodiments described above the valve 17 is intended to beconnected to a source of compressed air for the purpose of pumping upthe hose 2. If such a source is not available, the hose can be pumped bymeans of an ordinary bicycle pump. Then it is suitable as shown in Fig.l3to exchange the nipple 16 shown in Fig. 3 for a special nipple i6which is attached to one end of the cylinder 37 of a pump 3S providedwith an ordinary plunger by means, for instance, of the kind which isused for pumping up bicycle tires. The plunger shaft 39 of the pump, atthe outer end provided with a handle 4l turnably attached to the shaftby means of a pin 4t), is axially slidable through a housing 42 which isscrewed to the outer end of the nipple 16. The inner end of the cylinder37 is closed by means of a plug 43, in which is provided a valve i7suitably of the same type as shown in Fig. 3. Between the bore 12 andthe cylinder 37 of the pump there is an angular space 44 through whichthe air let in through the valve 17 can pass on to the channel 13 andfrom there to the space 14 between the shaft 1 and the hose 2. At theopposite end of the shaft a discharging valve may be arranged, so thatthe compressed air can be let out from the space 14 when the cardboardtube is to be removed.

Naturally further embodiments than those disclosed in the attacheddrawings fall within the scope of the invention. Also other expandingmeans than the hose 2 shown in the drawings can be used for the arc-likebending outwards of the bars 22, 22 and 22" of the expansible shell 3.

The mandrel can be provided with devices to protect the bars 22, 22 and22" of the expansible shell from being bent outwards by the internal airpressure to a degree above the elastic limit of the material. As anexample of such a device can be mentioned a sock or cover 45 (Fig. l2)of some strong textile material which is loosely passed over the hoseand which will be strained when the hose 2 is extended, and at a certaininternal pressure will stop further extension and bending outwards ofthe bars of the expansible shell 3.

I claim:

l. An expansible mandrel having an expansible shell and pneumatic meansadapted to actuate said shell radially and outwardly, said pneumaticmeans comprising a hose which is passed over a shaft passing through themandrel, means for securing the ends of said hose tightly to said shaftand means for letting in compressed air in a space between the hose andthe shaft, said expansible shell being provided outside round said hosewith a plurality of longitudinal bars the ends of which are carried bythe shaft to allow them to slide in the longitudinal direction of saidshaft without being displaced radially outwardly and to cause the middlepart of said bars to be bent bowlike outwardly due to the action of saidpneumatic means.

2. An expansible mandrel having an expansible shell and pneumatic meansadapted to actuate said shell radially and outwardly, said pneumaticmeans comprising a hose which is passed over a shaft passing through themandrel, means for securing the ends of said hose tightly to said shaftand means for letting in compressed air in a space between the hose andthe shaft, said expansible shell being provided outside and around saidhose with a number of longitudinal bars the ends of which are carried bythe shaft to allow them to slide iu the longitudinal direction of saidshaft without being displaced radially outwardly and to cause the middlepart of said bars to be bent bowlike outwardly due to the action of saidpneumatic means, said hose being provided at an end thereof with a clamphousing, an abutting part and with an expansible ring clasping said endof said hose and arranged to press said end of the hose into tighteningcontact with said shaft by cooperation between a clamp housing and anabutting part.

3, An expansible mandrel according to claim 2, wherein said expansiblering is a helically wound ring of steel material.

4. An expansible mandrel having an expansible shell and pneumatic meansadapted to actuate said shell radially outwards, said pneumatic meanscomprising a l hose which is passed over a shaft passing through themandrel, means for securing the ends of said hose tightly to said shaftand means for letting in compressed air in a space between the hose andthe shaft, said expansible shell being provided outside and around saidhose with a plurality of longitudinal bars the ends of which are carriedby the shaft to allow them to slide in the longitudinal direction ofsaid shaft without being displaced radially outwardly and to cause themiddle part of said bars to be bent bowlike outwardly due to the actionof said pneumatic means, said hose being provided at an end thereof witha clamp housing, an abutting part and with an expansible ring claspingsaid end of said hose and arranged to press said end of the hose intotightening contact with said shaft by cooperation between a clamphousing and an abutting part, said clamp housing being provided with aconical inner surface and being arranged to force said expansible ringwith its conical surface against said hose by moving said abutting partinto said clamp housing.

5. An expansible mandrel having an expansible shell and pneumatic meansadapted to actuate said shell radially and outwardly, said pneumaticmeans comprising a hose which is passed over a shaft passing through themandrel, means for securing the ends of said hose tightly to said shaftand means for letting in compressed air in a space between the hose andthe shaft, said expansible shell being provided outside and around saidhose with a plurality of longitudinal bars the ends of which are carriedby the shaft in a way to allow them to slide in the longitudinaldirection of said shaft without being displaced radially outwardly andto cause the middle part of said bars to be bent bowlike outwardly dueto the action of said pneumatic means, said longitudinal hose beingprovided at an end thereof with a piece of a hose of thin elasticmaterial, which is passed onto said shaft and is attached to saidlongitudinal hose in such a way that a part of said piece of hoseprotrudes freely into said longitudinal hose.

6. An expansible mandrel having an expansible shell and pneumatic meansadapted to actuate said shell radially and outwardly, said pneumaticmeans comprising a hose which is passed over a shaft passing through themandrel, means for securing the ends of said hose tightly to said shaftand means for letting in compressed air in a space between the hose andthe shaft, said expansible shell being provided outside and around saidhose with a plurality of longitudinal bars the ends of which are carriedby the shaft to allow them to slide in the longitudinal direction ofsaid shaft without being displaced radially outwardly and to cause themiddle part of said bars to be bent bowlike outwardly due to the actionof said pneumatic means, said shaft being provided with an axial borehaving a radial channel by means of which the bore communicates with aspace between said hose and said shaft.

7. An expansible mandrel according to claim 6 wherein the outer end ofsaid bore is provided with a valve having a valve seat and a valve plugwhich is arranged to be forced in tightening engagement against thevalve seat by means of the internal pneumatic pressure in the spacebetween said hose and said shaft.

8. An expansible mandrel having an expansible shell and pneumatic meansadapted to actuate said shell radially and outwardly, said pneumaticmeans comprising a hose which is passed over a shaft passing through themandrel, means for securing the ends of said hose tightly to said shaftand means for letting in compressed air in a space between the hose andthe shaft, said expansible shell being provided outside and around saidhose with a plurality of longitudinal bars the ends of which are ca:`ried by the shaft to allow them to slide in the longitudinal directionof said shaft without being displaced radially outwardly and to causethc middle part of said bars to be bent bowlike outwardly due to theaction of said pneumatic means, said shaft being provided with a tubi:having an axial bore and a radial channel by means of which the borecommunicates with a space between said hose and said shaft, and a valveapplied at both ends of said bore.

9. An expansible mandrel having an expansible shell and pneumatic meansadapted to actuate said shell radially and outwardly, said pneumaticmeans comprising a hose which is passed over a shaft passing through themandrel, means for securing the ends of said hose tightly to said shaftand means for letting in compressed air in a space between the hose andthe shaft, said expansible shell being provided outside round said hosewith a plurality of longitudinal bars the ends of which are carried bythe shaft to allow' them to slide in the longitudinal direction of saidshaft without being displaced radially outwardly and to cause the middlepart of said bars to be bent bowlike outwardly due to the action of saidpneumatic means, said shaft being provided with an axial bore and with aradial channel by means of which the bore communicates with a spacebetween said hose and said shaft, said bore being provided with a valveapplied at one end thereof and a plug entirely closing the bore at theopposite end thereof.

10. An expansible mandrel according to claim 8, wherein a plunger airpump is inserted in one end of said bore, a nipple attached to the endof the cylinder of said pump through which the plunger shaft passes and6 said cylinder being in operative tightening engagement with thecorresponding end of said shaft to position the valve applied at theopposite end of the pump cylinder inside of said bore.

11. An expansible mandrel having an expansible shell and pneumatic meansadapted to actuate said shell radially and outwardly, said pneumaticmeans comprising a hose which is passed over a shaft passing through themandrel, means for securing the ends of said hose tightly to said shaftand means for letting in compressed air in a space between the hose andthe shaft, said expansible shell being provided outside and around saidhose with a plurality of longitudinal bars the ends of which are carriedby the shaft to allow them to slide in the longitudinal direction ofsaid shaft without being displaced radially outwardly and to cause themiddle part of said bars to be bent bowlike outwardly due to the actionof said pneumatic means, said bars being arranged to provide the crosssection of said expansible shell in a polygonal shape.

l2. An expansible mandrel having an expansible shell and pneumatic meansadapted to actuate said shell radially and outwardly, said pneumaticmeans comprising a hose which is passed over a shaft passing through thei mandrel, means for securing the ends of said hose tightly to saidshaft and means for letting in compressed air in a space between thehose and the shaft, said expansible shell being provided outside andaround said hose with a plurality of longitudinal bars the ends of whichare carried by the shaft to allow them to slide in the longitudinaldirection of said shaft without being displaced radially outwardly andto cause the middle part of said bars to be bent bowlike outwardly dueto the action of said pneumatic means, a housing on said shaft, saidbars having their ends inserted into guides in the circumference of saidhousing on said shaft.

13. Au expansible mandrel according to claim 12, wherein said guideshave a dovetail-shaped cross section and the ends of said bars have sideedges which converge outwardly.

14. An expansible mandrel having an expansible shell and pneumatic meansadapted to actuate said shell radially outwards, said pneumatic meanscomprising a hose which is passed over a shaft passing through themandrel, means for securing the ends of said hose tightly to said shaftand means for letting in compressed air in a space between the hose andthe shaft, said expansible shell being provided outside and around saidhose with a plurality of longitudinal bars the ends of which are carriedby the shaft to allow them to slide in the longitudinal direction ofsaid shaft without being displaced radially outwardly and to cause themiddle part of said bars to be bent bowlike outwardly due to the actionof said pneumatic means, said hose further provided with a cover of astrong textile material, which loosely ts over said hose and is adaptedto be strained when the hose is extended to limit further extension andthe bending outwards of said bars of said extensible shell at apredetermined internal air pressure.

References Cited in the file of this patent UNlTED STATES PATENTS1,297,809 Dixon et al Mar. 18, 1919 2,106,799 Elvin et al Feb. 1, 19382,215,069 Meisel Sept. 17, 1940 2,365,980 Thomas Dec. 26, 1944 2,520,126Collard Aug. 29, 1950 2,621,867 Grettve Dec. 16, 1952 FOREIGN PATENTS16,629 Great Britain July 12, 1910

